x2-40x+396=0

Solution for x2-40x+396=0 equation:

x2-40x+396=0

We add all the numbers together, and all the variables

x^2-40x+396=0

a = 1; b = -40; c = +396;
Δ = b2-4ac
Δ = -402-4·1·396
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-40)-4}{2*1}=\frac{36}{2}
=18
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-40)+4}{2*1}=\frac{44}{2}
=22
$